Chip structure and process for forming the same

ABSTRACT

A chip structure comprises a substrate, a first built-up layer, a passivation layer and a second built-up layer. The substrate includes many electric devices placed on a surface of the substrate. The first built-up layer is located on the substrate. The first built-up layer is provided with a first dielectric body and a first interconnection scheme, wherein the first interconnection scheme interlaces inside the first dielectric body and is electrically connected to the electric devices. The first interconnection scheme is constructed from first metal layers and plugs, wherein the neighboring first metal layers are electrically connected through the plugs. The passivation layer is disposed on the first built-up layer and is provided with openings exposing the first interconnection scheme. The second built-up layer is formed on the passivation layer. The second built-up layer is provided with a second dielectric body and a second interconnection scheme, wherein the second interconnection scheme interlaces inside the second dielectric body and is electrically connected to the first interconnection scheme. The second interconnection scheme is constructed from at least one second metal layer and at least one via metal filler, wherein the second metal layer is electrically connected to the via metal filler. The thickness, width, and cross-sectional area of the traces of the second metal layer are respectively larger than those of the first metal layers.

This application is a continuation of application Ser. No. 10/997,145,filed on Nov. 24, 2004, now pending, which is a division of applicationSer. No. 10/690,205, filed on Oct. 20, 2003, now U.S. Pat. No.6,936,531, which is a division of application Ser. No. 10/337,673, filedon Jan. 6, 2003, now U.S. Pat. No. 6,700,162, which is a division ofapplication Ser. No. 10/124,388, filed on Apr. 15, 2002, now U.S. Pat.No. 6,756,259.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of a pending patentapplication Ser. No. 09/216791, filed Dec. 21, 1998, by M. S. Lin. Thepresent application is a continuation-in-part of a pending patentapplication Ser. No. 09/251183, filed Feb. 17, 1999, by M. S. Lin. Thepresent application is a continuation-in-part of a pending patentapplication Ser. No. 09/691497, filed Oct. 18, 2000, by M. S. Lin and J.Y. Lee. The present application is a continuation-in-part of a pendingpatent application Ser. No. 09/972639, filed Oct. 9, 2001, by M. S. Lin.All disclosures of these prior applications are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to a chip structure and a process forforming the same. More particularly, the invention relates to a chipstructure for improving the resistance-capacitance delay and a formingprocess thereof.

2. Description of the Related Art

Nowadays, electronic equipment are increasingly used to achieve manyvarious tasks. With the development of electronics technology,miniaturization, multi-function task, and comfort of utilization areamong the principle guidelines of electronic product manufacturers. Moreparticularly in semiconductor manufacture process, the semiconductordevices with 0.18 microns have been mass-produced. However, therelatively fine interconnections therein negatively impact the chip. Forexample, this causes the voltage drop of the buses, theresistance-capacitor delay of the key traces, and noises, etc.

FIG. 1 is a cross-sectional view showing a conventional chip structurewith interconnections.

As shown in FIG. 1, a chip structure 100 is provided with a substrate110, an built-up layer 120 and a passivation layer 130. There are plentyof electric devices 114, such as transistors, on a surface 112 of thesubstrate 110, wherein the substrate 110 is made of, for example,silicon. The built-up layer 120 provided with a dielectric body 122 andan interconnection scheme 124 is formed on the surface 112 of thesubstrate 110. The interconnection scheme 124 interlaces inside thedielectric body 122 and is electrically connected to the electricdevices 114. Further, the interconnection scheme 124 includes manyconductive pads 126 exposed outside the dielectric body 122 and theinterconnection scheme 124 can electrically connect with externalcircuits through the conductive pads 126. The dielectric body 122 ismade of, for instance, silicon nitride or silicon oxide. In addition,the passivation layer 130 is deposited on the built-up layer 120, andhas many openings respectively exposing the conductive pads 126. Theinterconnection scheme 124 includes at least one metal layer that canserve as a power bus or a ground bus. The power bus or the ground bus isconnected to at least one of the conductive pads 126 through which thepower bus or the ground bus can electrically connect with externalcircuits.

However, as far as the chip structure 100 is concerned,resistance-capacitance (RC) delay is easily generated because the linewidth of the interconnection scheme 124 is extremely fine, about below0.3 microns, the thickness of the interconnection scheme 124 isextremely thin, and the dielectric constant of the dielectric body 122is extremely high, about 4. Therefore, the chip efficiency drops off. Inparticular, the RC delay even usually occurs with respect to a powerbus, a ground bus or other metal lines transmitting common signals. Inaddition, the production of the interconnection scheme 124 withextremely fine line width is necessarily performed using facilities withhigh accuracy. This causes production costs to dramatically rise.

The present invention is related to a R.O.C. patent application Ser. No.88120548, filed Nov. 25, 1999, by M. S. Lin, issued Sep. 1, 2001, nowR.O.C. Pat. No. 140721. R.O.C. patent application Ser. No. 88120548claims the priority of pending U.S. patent application Ser. No.09/251183 and the subject matter thereof is disclosed in pending U.S.patent application Ser. No. 09/251183. The present invention is relatedto a R.O.C. patent application Ser. No. 90100176, filed Jan. 4, 2001, byM. S. Lin and J. Y. Lee, now pending. The subject matter of R.O.C.patent application Ser. No. 90100176 is disclosed in pending U.S. patentapplication Ser. No. 09/691497. The present invention is related to aJapanese patent application Ser. No. 200156759, filed Mar. 1, 2001, byM. S. Lin and J. Y. Lee, now pending. The present invention is relatedto a European patent application Ser. No. 01480077.5, filed Aug. 27,2001, by M. S. Lin and J. Y. Lee, now pending. The present invention isrelated to a Singaporean patent application Ser. No. 200101847-2, filedMar. 23, 2001, by M. S. Lin and J. Y. Lee, now pending. Japanese patentapplication Ser. No. 200156759, European patent application Ser. No.01480077.5, and Singaporean patent application Ser. No. 200101847-2claim the priority of pending U.S. patent application Ser. No. 09/691497and the subject matter of them is disclosed in pending U.S. patentapplication Ser. No. 09/691497.

SUMMARY OF THE INVENTION

Accordingly, an objective of the present invention is to provide a chipstructure and a process for forming the same that improvesresistance-capacitance delay and reduces energy loss of the chip.

Another objective of the present invention is to provide a chipstructure and a process for forming the same that can be produced usingfacilities with low accuracy. Therefore, production costs cansubstantially reduce.

To achieve the foregoing and other objectives, the present inventionprovides a chip structure that comprises a substrate, a first built-uplayer, a passivation layer and a second built-up layer. The substrateincludes many electric devices placed on a surface of the substrate. Thefirst built-up layer is located on the substrate. The first built-uplayer is provided with a first dielectric body and a firstinterconnection scheme, wherein the first interconnection schemeinterlaces inside the first dielectric body and is electricallyconnected to the electric devices. The first interconnection scheme isconstructed from first metal layers and plugs, wherein the neighboringfirst metal layers are electrically connected through the plugs. Thepassivation layer is disposed on the first built-up layer and isprovided with openings exposing the first interconnection scheme. Thesecond built-up layer is formed on the passivation layer. The secondbuilt-up layer is provided with a second dielectric body and a secondinterconnection scheme, wherein the second interconnection schemeinterlaces inside the second dielectric body and is electricallyconnected to the first interconnection scheme. The secondinterconnection scheme is constructed from at least one second metallayer and at least one via metal filler, wherein the second metal layeris electrically connected to the via metal filler. The thickness, width,and cross-sectional area of the traces of the second metal layer arerespectively larger than those of the first metal layers. In addition,the first dielectric body is constructed from at least one firstdielectric layer, and the second dielectric body is constructed from atleast one second dielectric layer. The individual second dielectriclayer is thicker than the individual first dielectric layer.

According to a preferred embodiment of the present invention, thethickness of the traces of the second metal layer ranges from 1 micronto 50 microns; the width of the traces of the second metal layer rangesfrom 1 micron to 1 centimeter; the cross sectional area of the traces ofthe second metal layer ranges from 1 square micron to 0.5 squaremillimeters. The first dielectric body is made of, for example, aninorganic compound, such as a silicon nitride compound or a siliconoxide compound. The second dielectric body is made of, for example, anorganic compound, such as polyimide (PI), benzocyclobutene (BCB), porousdielectric material, or elastomer. In addition, the above chip structurefurther includes at least one electrostatic discharge (ESD) circuit andat least one transitional device that are electrically connected to thefirst interconnection scheme. The transitional device can be a driver, areceiver or an I/O circuit. Moreover, the first interconnection schemeinclude at least one first conductive pad, at least one secondconductive pad, and at least one linking trace, wherein the openings ofthe passivation layer expose the first conductive pad and the secondconductive pad. The second conductive pad is electrically connected tothe second interconnection scheme. The first conductive pad is exposedto the outside. The linking trace connects the first conductive pad withthe second conductive pad and is shorter than 5,000 microns.

To sum up, the chip structure of the present invention can decline theresistance-capacitance delay, the power of the chip, and the temperaturegenerated by the driving chip since the cross sectional area, the widthand the thickness of the traces of the second metal layer are extremelylarge, since the cross sectional area of the via metal filler is alsoextremely large, since the second interconnection scheme can be made oflow-resistance material, such as copper or gold, since the thickness ofthe individual second dielectric layer is also extremely large, andsince the second dielectric body can be made of organic material, thedielectric constant of which is very low, approximately between1.about.3, the practical value depending on the applied organicmaterial.

In addition, the chip structure of the present invention can simplify adesign of a substrate board due to the node layout redistribution,fitting the design of the substrate board, of the chip structure by thesecond interconnection scheme and, besides, the application of the fewernodes to which ground voltage or power voltage is applied. Moreover, incase the node layout redistribution of various chips by the secondinterconnection scheme causes the above various chips to be providedwith the same node layout, the node layout, matching the same nodelayout of the above various chips, of the substrate board can bestandardized. Therefore, the cost of fabricating the substrate boardsubstantially drops off.

Moreover, according to the chip structure of the present invention, thesecond interconnection scheme can be produced using facilities with lowaccuracy. Therefore, production costs of the chip structure cansubstantially be reduced.

To achieve the foregoing and other objectives, the present inventionprovides a process for making the above chip structure. The process forfabricating a chip structure comprises the following steps.

Step 1: A wafer is provided with a plurality of electric devices, aninterconnection scheme and a passivation layer. Both the electricdevices and the interconnection scheme are arranged inside the wafer.The interconnection scheme is electrically connected with the electricdevices. The passivation layer is disposed on a surface layer of thewafer. The passivation layer has at least one opening exposing theinterconnection scheme. The largest width of the opening of thepassivation ranges from 0.5 microns to 200 microns

Step 2: A conductive layer is formed over the passivation layer of thewafer by, for example, a sputtering process, and the conductive layer iselectrically connected with the interconnection scheme.

Step 3: A photoresist is formed onto the conductive layer, and thephotoresist has at least one opening exposing the conductive layer.

Step 4: At least one conductive metal is filled into the opening of thephotoresist by, for example, a electroplating process, and theconductive metal is disposed over the conductive layer.

Step 5: The photoresist is removed.

Step 6: The conductive layer exposed to the outside is removed by, forexample, an etching process, and the conductive layer deposited underthe conductive metal remains. A signal is transmitted from one of theelectric devices to the interconnection scheme, then passes through thepassivation layer, and finally is transmitted to the conductive metal,and further, the signal is transmitted from the conductive metal to theinterconnection scheme with passing through the passivation layer, andfinally is transmitted to the other one or more of the electric devices.

Provided that two metal layers are to be formed, the process forfabricating the above chip structure further comprises the followingsteps:

Step 7: A dielectric sub-layer is formed over the passivation layer andcovers the formed conductive metal. The dielectric sub-layer has atleast one opening exposing the conductive metal formed at a lowerportion.

Step 8: At least other one conductive layer is formed on the dielectricsub-layer and into the opening of the dielectric sub-layer by, forexample, a sputtering process. The other conductive layer iselectrically connected with the metal layer exposed by the opening ofthe dielectric sub-layer.

Step 9: A photoresist is formed onto the other conductive layer, and thephotoresist having at least one opening exposing the other conductivelayer.

Step 10: At least other one conductive metal is filled into the openingof the photoresist by, for example, an electroplating process, and theother conductive metal disposed over the other conductive layer.

Step 11: The photoresist is removed.

Step 12: The other conductive layer exposed to the outside is removedby, for example, an etching process, and the other conductive layerdeposited under the other conductive metal remains.

Provided that multiple metal layers are to be formed, the sequentialsteps 7-12 are repeated at least one time.

To achieve the foregoing and other objectives, the present inventionprovides another process for making the above chip structure. Theprocess for fabricating a chip structure comprises the following steps.

Step 1: A wafer is provided with a plurality of electric devices, aninterconnection scheme and a passivation layer. Both the electricdevices and the interconnection scheme are arranged inside the wafer.The interconnection scheme is electrically connected with the electricdevices. The passivation layer is disposed on a surface layer of thewafer. The passivation layer has at least one opening exposing theinterconnection scheme.

Step 2: At least one conductive metal is formed over the passivationlayer of the wafer by, for example, a sputtering process, and theconductive metal is electrically connected with the interconnectionscheme.

Step 3: A photoresist is formed onto the conductive metal, and thephotoresist is patterned to expose the conductive metal to the outside.

Step 4: The conductive metal exposed to the outside is removed, and theconductive metal deposited under the photoresist remains.

Step 5: The photoresist is removed.

Provided that two metal layers are to be formed, the process forfabricating the above chip structure further comprises the followingsteps:

Step 6: A dielectric sub-layer is formed over the passivation layer andcovers the formed conductive metal. The dielectric sub-layer has atleast one opening exposing the conductive metal formed at a lowerportion.

Step 7: At least other one conductive metal is formed over thepassivation layer of the wafer by, for example, a sputtering process,and the other conductive metal electrically is connected with theconductive metal formed at a lower portion.

Step 8: A photoresist is formed onto the other conductive metal, and thephotoresist is patterned to expose the other conductive metal to theoutside.

Step 9: The other conductive metal exposed to the outside is removed,and the other conductive metal deposited under the photoresist remains.

Step 10: The photoresist is removed.

Provided that multiple metal layers are to be formed, the sequentialsteps 6-10 are repeated at least one time.

Both the foregoing general description and the following detaileddescription are exemplary and explanatory only and are not restrictiveof the invention, as claimed. It is to be understood that both theforegoing general description and the following detailed description areexemplary, and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention. A simple description of the drawings is asfollows.

FIG. 1 is a cross-sectional view schematically showing a conventionalchip structure with interconnections.

FIG. 2 is a cross-sectional view schematically showing a chip structureaccording to a first embodiment of the present invention.

FIG. 3 is a cross-sectional view schematically showing a chip structureaccording to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view schematically showing a chip structureaccording to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view schematically showing a chip structureaccording to a forth embodiment of the present invention.

FIG. 6 is a cross-sectional view schematically showing a chip structureaccording to a fifth embodiment of the present invention.

FIG. 7 is a cross-sectional view schematically showing a chip structureaccording to a sixth embodiment of the present invention.

FIG. 8 is a cross-sectional view schematically showing a chip structureaccording to a seventh embodiment of the present invention.

FIGS. 9-15 are various cross-sectional views schematically showing aprocess of fabricating a chip structure according to an embodiment ofthe present invention.

FIGS. 16-22 are various cross-sectional views schematically showing aprocess of fabricating a chip structure according to another embodimentof the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Prior to describing the embodiment of the invention, the factors of theresistance-capacitance delay and those of the power loss will beintroduced as the following equations.τ=RC=2ερL[L(T _(u.d.) T _(m))+L/(WS)]P∝2πfV ² kε(tan δ)

where .tau. is effect of resistance-capacitance delay; P is power loss;.ε is dielectric constant of dielectric material; ρ is resistance oftraces; L is trace length; W is trace width; S is pitch between traces;T_(u.d.) is thickness of dielectric material; T_(m) is trace thickness;tan δ is dielectric loss; V is applied voltage; f is frequency; k isfactor of capacitor structure.

According to the above equation, the factors of theresistance-capacitance delay and those of the power loss can be known.Therefore, an increase in thickness of every dielectric layer, anapplication of dielectric material with low dielectric constant, anapplication of traces with low resistance, or an increase in width orthickness of traces leads an effect of a resistance-capacitance delayand a power loss of a chip to decline.

According to the above conception, the present invention providesvarious improved chip structure. Please refer to FIG. 2, across-sectional view schematically showing a chip structure according toa first embodiment of the present invention. A chip structure 200 isprovided with a substrate 210, a first built-up layer 220, a passivationlayer 230 and a second built-up layer 240. There are plenty of electricdevices 214, such as transistors, on a surface 212 of the substrate 210,wherein the substrate 210 is made of, for example, silicon. The firstbuilt-up layer 220 is located on the substrate 210. The first built-uplayer 220 is formed by cross lamination of first metal multi-layers 226and first dielectric multi-layers. Moreover, plugs 228 connect the upperfirst metal layers 226 with the lower first metal layers 226 or connectthe first metal layers 226 with the electric devices 214. The firstmetal multi-layers 226 and the plugs 228 compose a first interconnectionscheme 222. The first dielectric multi-layers compose a first dielectricbody 224. The first interconnection scheme 222 interlaces inside thefirst dielectric body 224 and is electrically connected to the electricdevices 214. The first interconnection scheme 222 includes plenty ofconductive pads 227 (only shows one of them) that are exposed outsidethe first dielectric body 224. The first interconnection scheme 222 canelectrically connect with other circuits through the conductive pads227. The first dielectric body 224 is made of, for example, an inorganiccompound, such as a silicon oxide compound or a silicon nitridecompound. The material of the first interconnection scheme 222 includes,for example, copper, aluminum or tungsten. Provided that the firstinterconnection scheme 222 is formed by a copper process, the firstmetal layers 226 and the plugs 228 are made of copper. Provided that thefirst interconnection scheme 222 is formed by a general process, thefirst metal layers 226 are made of aluminum and the plugs 228 are madeof tungsten.

The passivation layer 230 is disposed on the first built-up layer 220and is provided with openings exposing the conductive pads 227. Thepassivation layer 230 is contructed of, for example, an inorganiccompound, such as a silicon oxide compound, a silicon nitride compound,phosphosilicate glass (PSG), a silicon oxide nitride compound or acomposite formed by laminating the above material.

The second built-up layer 240 is formed on the passivation layer 230.The second built-up layer 240 is formed by cross lamination of secondmetal multi-layers 246 and second dielectric multi-layers 241. Moreover,via metal fillers 248 connect the upper second metal layers 246 with thelower second metal layers 246 or connect the second metal layers 246with the conductive pads 227. The second metal layers 246 and the viametal fillers 248 compose a second interconnection scheme 242. Thesecond dielectric multi-layers 241 compose a second dielectric body 244.The second interconnection scheme 242 interlaces inside the seconddielectric body 244 and is electrically connected to the conductive pads227. The second interconnection scheme 242 includes plenty of nodes 247(only shows one of them). The second dielectric body 244 is providedwith openings 249 exposing the nodes 247 of the second interconnectionscheme 242. The second interconnection scheme 242 can electricallyconnect with external circuits through the nodes 247. The seconddielectric body 244 is made of, for example, an organic compound, suchas polyimide (PI), benzocyclobutene (BCB), porous dielectric material,parylene, elastomer, or other macromolecule polymers. The material ofthe second interconnection scheme 242 includes, for example, copper,aluminum, gold, nickel, titanium-tungsten, titanium or chromium. Becausemobile ions and moisture of the second built-up layer 240 can beprevented by the passivation layer 230 from penetrating into the firstbuilt-up layer 220 or the electric devices 214, it is practicable thatan organic compound and various metals are formed over thepassivationtion layer 230. The cross-sectional area A2 of the traces ofthe second metal layers 246 is extremely larger than the cross-sectionalarea A1 of the traces of the first metal layers 226 and than thecross-sectional area of the plugs 228. The cross-sectional area a of thevia metal fillers 248 is extremely larger than the cross-sectional areaA1 of the traces of the first metal layers 226 and than thecross-sectional area of the plugs 228. The trace width d2 of the secondmetal layers 246 is extremely larger than the trace width d1 of thefirst metal layers 226. The trace thickness t2 of the second metallayers 246 is extremely larger than the trace thickness t1 of the firstmetal layers 226. The thickness L2 of the individual second dielectriclayers 241 is extremely larger than the thickness L1 of the individualfirst dielectric layers of the first built-up layers 220. Thecross-sectional area a of the via metal fillers 248 is extremely largerthan the area, exposed outside the passivation layer 230, of theconductive pads 227. The trace width d2 of the second metal layers 246is larger than 1 micron, and preferably ranges from 1 micron to 1centimeter. The trace thickness t2 of the second metal layers 246 islarger than 1 micron, and preferably ranges from 1 micron to 50 microns.The cross-sectional area A2 of the second metal layers 246 is largerthan 1 square micron, and preferably ranges from 1 square micron to 0.5square millimeters. The cross-sectional area a of the via metal fillers248 is larger than 1 square micron, and preferably ranges from 1 squaremicron to 10,000 square microns. The thickness L2 of the individualsecond dielectric layers 241 is larger than 1 micron, and preferablyranges from 1 micron to 100 microns.

The above chip structure can decline the resistance-capacitance delay,the power of the chip, and the temperature generated by the driving chipsince the cross sectional area, the width and the thickness of thetraces of the second metal layers 246 are extremely large, since thecross sectional area of the via metal fillers 248 is also extremelylarge, since the second interconnection scheme 242 can be made oflow-resistance material, such as copper or gold, since the thickness L2of the individual second dielectric layers 241 is also extremely large,and since the second dielectric body 244 can be made of organicmaterial, the dielectric constant of which is very low, approximatelybetween 1.about.3, the practical value depending on the applied organicmaterial.

According to the above chip structure, the traces of the secondinterconnection scheme 242 are extremely wide and thick and thecross-sectional area of the via metal fillers 248 is extremely large.Thus, the second interconnection scheme 242 can be formed by low-costfabricating processes, such as an electroplating process, an electrolessplating process, or a sputtering process, and, moreover, the secondinterconnection scheme 242 can be produced using facilities with lowaccuracy. Therefore, the production costs of the chip structure can besubstantially saved. In addition, the request for the clean room wherethe second built-up layer is formed is not high, ranging from Class 10to Class 100. Consequently, the construction cost of the clean room canbe conserved.

The chip structure can simplify a design of a substrate board due to thelayout redistribution, fitting the design of the substrate board, of thenodes 247 of the chip structure by the second interconnection scheme 242and, besides, the application of the fewer nodes 247 to which groundvoltage or power voltage is applied. Moreover, in case the layoutredistribution of nodes 247 of various chips by the secondinterconnection scheme 242 causes the above various chips to be providedwith the same node layout, the node layout, matching the same nodelayout of the above various chips, of the substrate board can bestandardized. Therefore, the cost of fabricating the substrate boardsubstantially drops off.

Next, other preferred embodiments of the present invention will beintroduced. As a lot of electric devices are electrically connected witha power bus and a ground bus, the current through the power bus and theground bus is relatively large. Therefore, the second interconnectionscheme of the second built-up layer can be designed as a power bus or aground bus, as shown in FIG. 3. FIG. 3 is a cross-sectional viewschematically showing a chip structure according to a second embodimentof the present invention. The first interconnection scheme 322 of thebuilt-up layer 320 electrically connects the second interconnectionscheme 342 of the built-up layer 340 with the electric devices 314 andat least one electrostatic discharge circuit 316, wherein theelectrostatic discharge circuit 316 is disposed on the surface 312 ofthe substrate 310. As a result, provided that the second interconnectionscheme 342 is designed as a power bus, the second interconnection scheme342 electrically connects with the power ends of the electric devices314. Provided that the second interconnection scheme 342 is designed asa ground bus, the second interconnection scheme 342 electricallyconnects with the ground ends of the electric devices 314. The secondmetal layer 346 of the power bus or that of the ground bus can be of,for example, a planer type. According to the above chip structure, eachof the power buses or the ground buses can electrically connect withmore electric devices 314 than that of prior art. Consequently, thenumber of the power buses or the ground buses can be reduced and, also,the number of the electrostatic discharge circuits 316 accompanying thepower buses or the ground buses can be reduced. In addition, the numberof the nodes 347 accompanying the power buses or the ground buses can bereduced. Thus, the circuit layout can be simplified and the productioncost of the chip structure 300 can be saved. The electrostatic dischargecircuits 316 can prevent the electric devices 314 electrically connectedwith the second interconnection scheme 344 from being damaged by thesudden discharge of high voltage. In addition, the chip structure 300can be electrically connected with external circuits through the nodes347 applying a flip-chip type, a wire-bonding type or atape-automated-bonding type.

Referring to FIG. 4, FIG. 4 is a cross-sectional view schematicallyshowing a chip structure according to a third embodiment of the presentinvention. There are many electric devices 414, many electrostaticdischarge circuits 416 (only shows one of them) and many transitiondevices 418 (only shows one of them) on the surface 412 of the substrate410. The first interconnection scheme 422 is divided into firstinterconnections 422 a and first transition interconnections 422 b. Thesecond interconnection scheme 442 is divided into secondinterconnections 442 a and second transition interconnections 442 b.Consequently, the nodes 447 are electrically connected with thetransition devices 418 and the electrostatic discharge circuits 416through the first transition interconnections 422 b and the secondtransition interconnections 442 b. The transition devices 418 areelectrically connected with the electric devices 414 through the firstinterconnections 422 a and the second interconnections 442 a. Forexample, this circuit layout can be to transmit clock signals. Theelectrostatic discharge circuits 416 can prevent the electric devices414 and the transition devices 418 from being damaged by the suddendischarge of high voltage. In addition, the chip structure can beelectrically connected with external circuits through the nodes 447applying a flip-chip type, a wire-bonding type or atape-automated-bonding type.

Referring to FIG. 5, FIG. 5 is a cross-sectional view schematicallyshowing a chip structure according to a forth embodiment of the presentinvention. The second metal layer 1546 of the second interconnectionscheme 1542 is directly formed on the passivation layer 1530. Thus, thesecond metal layer 1546 of the second interconnection scheme 1542 can bedirectly electrically connected with the conductive pads 1527, exposedoutside the passivation layer 1530, of the first interconnection scheme1522. In addition, the chip structure can be electrically connected withexternal circuits through the nodes 1547 applying a flip-chip type, awire-bonding type or a tape-automated-bonding type.

According to the above embodiment, a second built-up layer isconstructed from a second dielectric body and a second interconnectionscheme. However, a second built-up layer also can be composed of only asecond interconnection scheme, as shown in FIG. 6. FIG. 6 is across-sectional view schematically showing a chip structure according toa fifth embodiment of the present invention. The second metal layer 1646of the second interconnection scheme is directly formed on thepassivation layer 1630 and can be directly electrically connected withthe conductive pads 1627, exposed outside the passivation layer 1630, ofthe first interconnection scheme 1622. The second metal layer 1646 isexposed to the outside. In addition, the chip structure can beelectrically connected with external circuits by bonding wires onto thesecond metal layer 1646.

According to the above chip structure, bumps or wires are directlyelectrically connected with the second interconnection layer. However,the application of the present invention is not limited to the aboveembodiment. Bumps or wires also can be directly connected withconductive pads and, besides, through the first interconnection scheme,the bumps or the wires can be electrically connected with the secondinterconnection scheme, as shown in FIG. 7 and FIG. 8. FIG. 7 is across-sectional view schematically showing a chip structure according toa sixth embodiment of the present invention. FIG. 8 is a cross-sectionalview schematically showing a chip structure according to a seventhembodiment of the present invention.

Referring to FIG. 7, in the chip structure 700, the conductive pads 727a are exposed to the outside and the conductive pads 727 b are directlyelectrically connected with the second metal layer 746. The chipstructure 700 can be electrically connected with external circuits bybonding wires (not shown) onto the conductive pads 727 a. Though thefirst transition interconnections 722 b, the conductive pads 727 a areelectrically connected with the electrostatic discharge circuits 716 andthe transition devices 718 respectively. Though the firstinterconnections 722 a, the conductive pads 727 b and the second metallayer 746, the transition devices 718 are electrically connected withthe electric devices 714. In addition, bumps also can be formed on theconductive pads 727 a, and the chip structure 700 can be electricallyconnected with external circuits through the bumps.

Referring to FIG. 8, in the chip structure 800, the conductive pads 827a are exposed to the outside and the conductive pads 827 b are directlyelectrically connected with the second interconnection scheme 842.Linking traces 829 connect the conductive pads 827 a with the conductivepads 827 b. The chip structure 800 can be electrically connected withexternal circuits by bonding wires (not shown) onto the conductive pads827 a. Though the linking traces 829 and conductive pads 827 b, theconductive pads 827 a are electrically connected with the secondinterconnection scheme 842. Though the first interconnection scheme 822,the second interconnection scheme 842 is electrically connected with theelectric devices 814. In addition, bumps (not shown) also can be formedon the conductive pads 827 a, and the chip structure 800 can beelectrically connected with external circuits through the bumps. Theshorter the length S of the linking traces 829, the better theelectrical efficiency of the chip structure 800. Otherwise, it ispossible that the resistance-capacitance delay and the voltage drop willoccur and the chip efficiency will be reduced. It is preferred that thelength S of the linking traces 829 is less than 5,000 microns.

Following, the second built-up layer of the present invention will bedescribed. FIGS. 9-15 are various cross-sectional views schematicallyshowing a process of fabricating a chip structure according to anembodiment of the present invention.

First, referring to FIG. 9, a wafer 502 is provided with a substrate510, a first built-up layer 520 and a passivation layer 530. There areplenty of electric devices 514 on a surface 512 of the substrate 510.The first built-up layer 520 is formed on the substrate 5 10. The firstbuilt-up layer 520 includes a first interconnection scheme 522 and afirst dielectric body 524, wherein the first interconnection scheme 522interlaces inside the first dielectric body 524 and is electricallyconnected to the electric devices 514. The first dielectric body 524 isconstructed from the lamination of first dielectric multi-layers 521.The first interconnection scheme 522 includes first metal multi-layers526 and plugs 528. Through the plugs 528, the first metal layers 526 canbe electrically connected with the electric devices 514 or the firstmetal layers 526 neighbored. The first interconnection scheme 522further includes one or more conductive pads 527 (only shows one ofthem) that are exposed outside the first dielectric body 524. Thepassivation layer 530 is formed on the first built-up layer 520 and isprovided with one or more openings 532 exposing the conductive pads 527.The largest width of the openings 532 ranges from 0.5 to 200 microns forexample. Because the openings 532 can be formed relatively small, forexample, the largest width of the openings 532 ranging from 0.5 to 20microns, and, correspondingly, the conductive pads 527 can be formedrelatively small, the routing density of the top metal layer having theconductive pads 527 can be enhanced. Moreover, due to the design of theopenings 532 with relatively small dimensions and high density,correspondingly, the circuits, connecting with the conductive pads 527,of the second interconnection scheme can be formed small. As a result,the parasitic capacitance generated by the second interconnection schemecan become relatively small.

Next, a second dielectric sub-layer 541 is formed on the passivationlayer 530 by, for example, a spin-coating process, wherein the seconddielectric sub-layer 541 is made of, for instance, photosensitiveorganic material. Subsequently, one or more via metal openings 543 areformed through the second dielectric sub-layer 541 using, for example, aphotolithography process. The via metal openings 543 expose theconductive pads 527. In case that the width of the openings 532 is verysmall, such as 1 micron, the width of the via metal openings 543 can bedesigned to be larger than that of the openings 532. This leadsconductive metals, during the following metal-filling process, to beeasily filled into the via metal openings 543 and the openings 532. Forinstance, the width of the via metal openings 543 is 3 microns or largerthan 3 microns.

Next, referring to FIG. 10, by, for example, a sputtering process, aconductive layer 560 is formed onto the second dielectric sub-layer 541,onto the side walls of the via metal openings 543, and onto thepassivation layer 530 and the conductive pads 527 exposed by the viametal openings 543. The conductive layer 560 is made of, for example,titanium-tungsten, titanium or chromium. Subsequently, as shown in FIG.11, a photoresist 550 is formed onto the conductive layer 560. Then, by,for example, an exposing process and a lithography process, photoresistopenings are formed where a second metal layer is demanded to befabricated and pass through the photoresist 550 to expose the conductivelayer 560. Subsequently, by, for example, an electroplating process, oneor more conductive metals 580 are filled into the via metal openings 543and the photoresist openings 552 as shown in FIG. 12, and are formedover the conductive layer 560. Foe example, the conductive metals 580include copper, gold, or nickel. Thereafter, the photoresist 550 isremoved as shown in FIG. 13.

Following, referring to FIG. 14, the conductive layer 560 exposed to theoutside is removed and only remains the conductive layer 560 disposedunder the conductive metals 580. Next, referring to FIG. 15, by, forexample, a spin-coating process, another second dielectric sub-layer 570is formed onto the conductive metals 580 and onto the second dielectricsub-layer 541 located at the lower portion. The second dielectricsub-layer 570, latest formed at the higher portion, is made of, forexample, photosensitive material. Subsequently, by, for example, aphotolithography process, one or more node openings 572 are formedthrough the second dielectric sub-layer 570 located at the higherportion such that the node openings 572 expose the top conductive metal580. The exposed conductive metal 580 is defined as nodes 547, throughwhich the chip structure 500 can be electrically connected with externalcircuits. The second built-up layer 540 is completed so far. The secondbuilt-up layer 540 includes a second interconnection scheme 542 and asecond dielectric body 544, wherein the second interconnection scheme542 interlaces inside the second dielectric body 544. The secondinterconnection scheme 542 includes at least one second metal layer 546and at least one via metal filler 548. The via metal filler 548 isconstructed from the conductive metals 580 and the conductive layer 560that are disposed in the via metal opening 543. The second metal layer546 is constructed from the conductive metals 580 and the conductivelayer 560 that are outside the via metal opening 543 and on the seconddielectric sub-layer 541. The via metal filler 548 electrically connectsthe second metal layers 546 with the conductive pads 527. When thecross-sectional area of the opening 532 is very small, thecross-sectional area of the via metal opening 543 can be designed to belarger than that of the opening 532. The second dielectric body 544 isconstructed from the lamination of the second dielectric multi-layers541, 570. The thickness L2 of the second dielectric layers 541, 570 isextremely larger than the thickness L1 of the first dielectric layers521. The thickness L2 of the second dielectric layers 541, 570 rangesfrom 1 micron to 100 microns. The structure, material, and dimension ofthe second built-up layer 540 are detailed in the previous embodiments,and the repeat is omitted herein.

Besides, the chip structure of the present invention can also beperformed by the other process, described as follows. FIGS. 16-22 arevarious cross-sectional views schematically showing a process offabricating a chip structure according to another embodiment of thepresent invention.

First, referring to FIG. 16, a wafer 602 is provided. The internalstructure of the wafer 602 is detailed as the previous embodiments, andthe repeat is omitted herein. Next, a second dielectric sub-layer 641 isformed onto the passivation layer 630 of the wafer 602 by, for example,a spin-coating process, wherein the second dielectric sub-layer 641 ismade of, for instance, photosensitive material. Subsequently, one ormore via metal openings 643 are formed through the second dielectricsub-layer 641 by, for example, a photolithography process. The via metalopenings 643 expose the conductive pads 627. In case that the width ofthe openings 632 is very small, the width of the via metal openings 643can be designed to be larger than that of the openings 632. This leadsconductive metals, during the following metal-filling process, to beeasily filled into the via metal openings 643 and the openings 632.

Subsequently, referring to FIG. 17, by, for example, a sputteringprocess, a conductive layer 660 is formed onto the second dielectricsub-layer 641, onto the side walls of the via metal openings 643, andonto the passivation layer 630 and the conductive pads 627 exposed bythe via metal openings 643. The conductive layer 660 is made of, forexample, titanium-tungsten, titanium or chromium.

Following, referring to FIG. 18, one or more conductive metals 680 areformed onto the conductive layer 660 and into the via metal openings643, by, for example, an electroplating process or a sputtering process.Foe example, the conductive metals 680 include copper, aluminum, gold,or nickel. Thereafter, referring to FIG. 19, a photoresist 650 is formedonto the conductive metals 680 and then by, for example, an exposureprocess and a lithography process, the photoresist 650 is defined with aline pattern. Only remains the photoresist 650 where a second metallayer is demanded to be formed, and the conductive metals 680 that isnot demanded to be formed as the second metal layer is exposed to theoutside. Subsequently, referring to FIG. 20, by, for example, an etchingprocess, the conductive metals 680 exposed outside the photoresist 650are removed. Thereafter, the conductive layer 660 exposed outside theconductive metals 680 are removed by, for example, another etchingprocess. Next, the photoresist 650 is removed, as shown in FIG. 21.

Next, referring to FIG. 22, by, for example, a spin-coating process,another second dielectric sub-layer 670 is formed onto the conductivemetals 680 and onto the second dielectric sub-layer 641 located at thelower portion. The second dielectric sub-layer 670, latest formed at thehigher portion, is made of, for example, photosensitive material.Subsequently, by, for example, a photolithography process, one or morenode openings 672 are formed through the second dielectric sub-layer 670located at the higher portion such that the node openings 672 expose thetop conductive metal 680. The exposed conductive metal 680 is defined asnodes 647, through which the chip structure 600 can be electricallyconnected with external circuits. The structure, material, and dimensionof the second built-up layer 640 are detailed in the previousembodiments, and the repeat is omitted herein.

In addition, according to the above process, the present invention isnot limited to the application of the second metal layer with a signallayer. However, second metal multi-layers also can be applied in thepresent invention. The fabrication method of the second metalmulti-layers is to repeat the above fabrication method of the secondmetal layer with a single layer. The second built-up layer, with secondmetal multi-layers, fabricated by the above whatever process is finallyformed with a second dielectric sub-layer having node openings thatexpose the second interconnection scheme to be electrically connectedwith external circuits. Alternatively, the whole surface of the secondmetal layer at the top portion can be exposed to the outside, andthrough bumps or conducting wires, the second metal layer can beelectrically connected with external circuits. Besides, when the secondmetal layers is over 2 layers, the via metal openings of the seconddielectric sub-layer at a higher portion expose the second metal layerat a lower portion so that the conductive metals disposited in the viametal openings electrically connect the upper second metal layer withthe lower second metal layer.

To sum up, the present invention has the following advantages:

1. The chip structure of the present invention can decline theresistance-capacitance delay, the power of the chip, and the temperaturegenerated by the driving chip since the cross sectional area, the widthand the thickness of the traces of the second metal layer are extremelylarge, since the cross sectional area of the via metal filler is alsoextremely large, since the second interconnection scheme can be made oflow-resistance material, such as copper or gold, since the thickness ofthe individual second dielectric layer is also extremely large, andsince the second dielectric body can be made of organic material, thedielectric constant of which is very low, approximately between1.about.3, the practical value depending on the applied organicmaterial.

2. According to the chip structure of the present invention, each of thepower buses or the ground buses can electrically connect with moreelectric devices than that of prior art. Consequently, the number of thepower buses or the ground buses can be reduced and, also, the number ofthe electrostatic discharge circuits accompanying the power buses or theground buses can be reduced. In addition, the number of the nodesaccompanying the power buses or the ground buses can be reduced. Thus,the circuit layout can be simplified and the production cost of the chipstructure can be saved. The electrostatic discharge circuits can preventthe electric devices electrically connected with the secondinterconnection scheme from being damaged by the sudden discharge ofhigh voltage.

3. The chip structure of the present invention can simplify a design ofa substrate board due to the node layout redistribution, fitting thedesign of the substrate board, of the chip structure by the secondinterconnection scheme and, besides, the application of the fewer nodesto which ground voltage or power voltage is applied. Moreover, in casethe node layout redistribution of various chips by the secondinterconnection scheme causes the above various chips to be providedwith the same node layout, the node layout, matching the same nodelayout of the above various chips, of the substrate board can bestandardized. Therefore, the cost of fabricating the substrate boardsubstantially drops off.

4. According to the chip structure of the present invention, the secondinterconnection scheme can be produced using facilities with lowaccuracy. Therefore, production costs of the chip structure cansubstantially be reduced.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. A method for fabricating a chip, comprising: providing a siliconsubstrate, a transistor in or on said silicon substrate, a first metallayer over said silicon substrate, a second metal layer over saidsilicon substrate, a dielectric layer between said first and secondmetal layers, a pad over said silicon substrate, wherein said pad has atop surface with a first region and a second region surrounding saidfirst region, and a passivation layer over said semiconductor substrate,over said first and second metal layers, over said dielectric layer andon said second region, wherein said passivation layer comprises atopmost inorganic insulating layer of said chip, wherein a first openingin said passivation layer is over said first region and exposes saidfirst region, wherein said first opening has a width between 0.5 and 20micrometers; forming a first organic layer on said passivation layer,wherein said first organic layer has a thickness between 1 and 100micrometers and greater than that of said passivation layer and that ofsaid dielectric layer, and wherein a second opening in said firstorganic layer is over said first region and exposes said first region;forming a first metal layer on said first organic layer and on saidfirst region, wherein said first metal layer comprises titanium; forminga photoresist layer on said first metal layer, wherein an opening insaid photoresist layer exposes said first metal layer; electroplating asecond metal layer on said first metal layer exposed by said opening insaid photoresist layer, wherein said second metal layer comprisescopper; removing said photoresist layer; and removing said first metallayer not under said second metal layer.
 2. The method of claim 1,wherein said forming said first metal layer comprises a sputteringprocess.
 3. The method of claim 1, wherein said forming said firstorganic layer comprises forming a polyimide layer on said passivationlayer.
 4. The method of claim 1, wherein said forming said first organiclayer comprises forming a benzocyclobutene layer on said passivationlayer.
 5. The method of claim 1, wherein said forming said first organiclayer comprises a spin-on coating process.
 6. The method of claim 1,after said removing said first metal layer not under said second metallayer, further comprising forming a second organic layer on said firstorganic layer and on said second metal layer.
 7. The method of claim 1,wherein said second metal layer further comprises nickel.
 8. A methodfor fabricating a chip, comprising: providing a silicon substrate, atransistor in or on said silicon substrate, a first metal layer oversaid silicon substrate, a second metal layer over said siliconsubstrate, a dielectric layer between said first and second metallayers, a pad over said silicon substrate, wherein said pad has a topsurface with a first region and a second region surrounding said firstregion, and a passivation layer over said semiconductor substrate, oversaid first and second metal layers, over said dielectric layer and onsaid second region, wherein said passivation layer comprises a topmostinorganic insulating layer of said chip, wherein a first opening in saidpassivation layer is over said first region and exposes said firstregion, wherein said first opening has a width between 0.5 and 20micrometers; forming a first organic layer on said passivation layer,wherein said first organic layer has a thickness between 1 and 100micrometers and greater than that of said passivation layer and that ofsaid dielectric layer, and wherein a second opening in said firstorganic layer is over said first region and exposes said first region;and forming a first metal layer on said first organic layer and on saidfirst region; forming a photoresist layer on said first metal layer,wherein an opening in said photoresist layer exposes said first metallayer; electroplating a second metal layer on said first metal layerexposed by said opening in said photoresist layer, wherein said secondmetal layer comprises copper; removing said photoresist layer; andremoving said first metal layer not under said second metal layer. 9.The method of claim 8, wherein said forming said first metal layercomprises a sputtering process.
 10. The method of claim 8, wherein saidforming said first organic layer comprises forming a polyimide layer onsaid passivation layer.
 11. The method of claim 8, wherein said formingsaid first organic layer comprises forming a benzocyclobutene layer onsaid passivation layer.
 12. The method of claim 8, wherein said formingsaid first organic layer comprises a spin-on coating process.
 13. Themethod of claim 8, after said removing said first metal layer not undersaid second metal layer, further comprising forming a second organiclayer on said first organic layer and on said second metal layer. 14.The method of claim 8, wherein said forming said first metal layercomprises forming a chromium layer on said first organic layer and onsaid first region.
 15. The method of claim 8, wherein said second metallayer further comprises nickel.
 16. A method for fabricating a chip,comprising: providing a silicon substrate, a transistor in or on saidsilicon substrate, a first metal layer over said silicon substrate, asecond metal layer over said silicon substrate, a dielectric layerbetween said first and second metal layers, a pad over said siliconsubstrate, wherein said pad has a top surface with a first region and asecond region surrounding said first region, and a passivation layerover said semiconductor substrate, over said first and second metallayers, over said dielectric layer and on said second region, whereinsaid passivation layer comprises a topmost inorganic insulating layer ofsaid chip, wherein a first opening in said passivation layer is oversaid first region and exposes said first region, wherein said firstopening has a width between 0.5 and 20 micrometers; forming a firstmetal layer over said passivation layer and on said first region;forming a photoresist layer on said first metal layer, wherein anopening in said photoresist layer exposes said first metal layer;electroplating a second metal layer on said first metal layer exposed bysaid opening in said photoresist layer, wherein said second metal layercomprises copper; removing said photoresist layer; and removing saidfirst metal layer not under said second metal layer.
 17. The method ofclaim 16, wherein said forming said first metal layer comprises asputtering process.
 18. The method of claim 16, wherein said formingsaid first metal layer comprises forming a chromium layer on said firstorganic layer and on said first region.
 19. The method of claim 16,wherein said forming said first metal layer comprises forming atitanium-containing layer on said first organic layer and on said firstregion.
 20. The method of claim 16, wherein said second metal layerfurther comprises nickel.